Treatment of herpes simplex labialis with topical acyclovir in polyethylene glycol.

A double-blind, placebo-controlled trial of topical 5% acyclovir (ACV) in polyethylene glycol (PEG) was carried out among 208 patients who had an episode of herpes simplex labialis. Patients who were treated with ACV had a greater decrease in median titers of virus in lesions between the first and second visits to the clinic than did patients who were treated with placebo (-1.5 log pfu [plaque-forming units] vs. -0.2 log pfu; P = 0.04). The antiviral effect occurred in the subgroup of patients who entered the study 0-8 hr after the onset of lesions. No differences were noted in the remaining patients who began treatment 9-25 hr after onset. An examination of the subgroup who had virus-positive specimens before treatment revealed prominent and more statistically significant virologic differences between treatment groups. No clinical benefit from treatment with ACV was observed; however, the present study describes the first antiviral effect of topical treatment for recurrent herpes labialis and identifies treatment strategies for future studies.